柴油机分流气体对冲耦合消声器压力损失研究

Study on Pressure Loss of the Split-stream Rushing Coupled Mufflers of Diesel Engines

消声器设计中消声量与排气背压之间是相互矛盾且需要反复权衡的关系,同时消声器消声量、排气背压、气流通过性等性能评价指标与其内部气流速度有直接关系即内部气流速度越大,总体性能参数越差。以降低消声器内部气流速度为出发点,基于分流气体对冲降速原理,结合传统消声单元获得新型耦合结构消声器,并对其压力损失进行研究。采用理论分析、数值仿真和测试试验的方法,分析分流气体对冲结构的降速原理,并对新型耦合结构消声器压力损失进行研究。结果表明:气体经过对冲腔前后速度从57.6 m/s降为28.7 m/s,对冲腔压力较原装消声器降低1.67 kPa,消声器内部湍动能场强度小于原装消声器,试验结果表明新型耦合结构消声器压力损失和出口气流速度比原装消声器均降低20%以上。该新型耦合结构消声器的气流通过性能、压力损失、出口气流速度均优于原装消声器。

In the design of mufflers, there is a trade-off relationship between the noise elimination and exhaust back pressure. The performance evaluation indicators, such as noise elimination of the muffler, exhaust back pressure and airflow possibility, are directly related to the internal airflow velocity, that is, the faster the internal airflow velocity is, the worse the overall performance is. In this paper, under the premise of reducing the internal airflow velocity of the muffler, based on the principle of the shunt gas to reduce the speed, and combined with the traditional muffler unit, a new type muffler with coupling structure is designed. Using the methods of theoretical analysis, numerical simulation and experiment test, the speed reduction principle of the split gas hedging structure is analyzed, and the pressure loss of the new coupled structure muffler is studied. The simulation results show that the speed of the gas is reduced from 57.6 m/s to 28.7 m/s after passing the hedging cavity. The pressure of the hedging cavity is 1.67 k Pa lower than that of the original muffler. The intensity of the turbulent kinetic energy field inside the muffler is less than that of the original muffler. The test results show that the pressure loss of the new coupling structure muffler and the outlet air velocity is lower than the original muffler by more than 20 %.The airflow performance, pressure loss, and outlet airflow velocity of the new coupled structure muffler are all better than those of the original muffler.